Electron gun assembly having cathodes insulatively mounted in metallic plate

ABSTRACT

For the multi-gun assembly of a cathode ray tube, a unitary cathode mounting plate provided with integral beading spaced, and having three apertures - in either delta or in-line configuration - within which cathode eyelets are glass-frit mounted. Conventional cathode and cathode heater structure is associated with each of the eyelets insulatively secured to the plate by the glass frit.

I United States Patent 1 1 1 1 3,732,459 Mayers 1 1 May 8, 1973 [54]ELECTRON GUN ASSEMBLY HAVING [56] References Cited CATHODES INSULATIVELYMOUNTED IN METALLIC PLATE UNITED STATES PATENTS 2,645,734 7/1953Rajchman ..313/68 [75 1 Inventor E s: Mayers Hummgdo val 2,957,10610/1960 Moodey ..313 70 c x 3,244,927 4/1966 Drake et al 1 ..313/270[73] Assignee: Philco-Ford Corporation, Philadel- 3-443-316 6/1969Yoshida ct C phia 3,569,768 3 1971 Benda ..313 270 3,575,626 4/1971Blumenberg ..313/70 C 22 Filed: Aug. 20, 1971 Primar Examiner-Robert Sea1 21 A LN 173,697 y g I pp 0 AttorneyCar] H. Synnestvedt Related US.Application Data [57] ABSTRACT [63] Continuation of Ser. No. 873,361,Nov. 3, 1969,

abandoned. For the multi-gun assembly of a cathode ray tube, a unitarycathode mounting plate provided with integral [52] U.S.Cl. ..313/70R,313/7OC,313/270 beading spaced, and having three apertures in [51]Int. Cl ..H01j 29/04, HOlj 29/50 either delta or in-line configurationwithin which [58] Field of Search..' ..313/69, 69 C, 70, cathode eyeletsare glass-frit mounted. Conventional 1 Claim, 5 Drawing Figures ELECTRONGUN ASSEMBLY HAVING CATHODES INSULATIVELY MOUNTED IN METALLIC PLATE Thisapplication is a continuation of Ser. No. 873,361, filed Nov. 3, 1969,abandoned.

BACKGROUND OF THE INVENTION This invention relates to an electron gunassembly, and is directed especially to improvements in electron gunassemblies of the type used in color cathode ray tubes. 7

In one well known electron gun assembly of the aforementioned type, thecathode structure comprises threeseparate cathode elements assembled oninsulative rods. Manufacture of these separate elements, and assemblythereof into the gun structure, is time consuming and involvespainstaking alignment procedures.

SUMMARY OF THE INVENTION The present invention is directed toimprovement of such cathode structure, looking to improvements in theoverall assembly of the gun and simplification of the alignmentproblems.

In achievement of the foregoing as well as other objectives, theinvention contemplates provision of a single cathode plate to serve assupport means for the cathode elements of a plural electron gunassembly. Each of the cathode elements is located in an eyelet that ismounted in an aperture in the metal cathode plate by means of glass fritthat not only joins the eyelet to the support plate, but also serves asan insulator preventing electrical contact between the eyelet and theplate. In the fabrication of the above described assembly, the cathodesupport plate and its associated support are fabricated as a singleunit, having three apertures for receiving the eyelets. The cathodeeyelets are provided with a head of glass frit paste and are pushedthrough the plate apertures and into position so that the frit occupiesthe space between the eyelet and the support plate. The subassembledplate and eyelets are placed in a jig and fired to fuse the glass frit.The cathode plate and its associated eyelets are then ready forinsertion of the cathode and heater therein, in accordance withconventional practice. The invention contemplates that the cathodearrangement be of either in-line or delta configuration.

The manner in which the foregoing as well as other objectives may bestbe achieved will be more fully understood from a consideration of thefollowing description taken in light of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational showing,partly in section and with parts broken away, of a cathode ray tubeembodying electron gun structure made in accordance with one aspect ofthe invention;

FIG. 2 is an enlarged sectional view of apparatus illustrated in FIG. 1,as seen looking generally in the direction of arrows 2-2 appliedthereto;

FIG. 3 is a sectional view of a portion of the gun structure illustratedin FIG. 2, as seen looking in the direction of arrows 3-3 appliedthereto, and showing further details of the particular cathode structurecontemplated by the invention; and

FIGS. 4 and 5 are views similar to FIGS. 2 and 3,'and illustrating amodified embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With more particular referenceto the drawing, and first to FIG. 1, an electron gun assembly 10 madeaccording to the invention is mounted in the neck 11 ofa cathode raytube having substantial portions broken away for convenience ofillustration. Gun assembly 10 includes three individual guns only one ofwhich is shown in FIG. 1, at 12, and each comprising tubular andcupshaped, axially aligned grids on insulative support rods 14 mountedin conventional manner on certain ones of connector pins 15. The grids,or electrodes, are electrically connected to appropriate ones of theterminal pins 15 extending through the base portion of tube neck 11.With reference also to FIGS. 2 and 3, the

guns 12 are disposed in delta array. That is, they are spaced atsubstantially equal radial distances about the axis of the tube neck 11.The several grids of each gun comprise the control grid 16, acceleratinggrid 17 and focus grids 18, 18a, 18b, the latter supporting aconvergence shield 19 electrically connected by the usual springsnubbers (not shown) to the inside conductive coating of the picturetube.

The gun grids cooperate with one another, with cathodes and cathodeheaters therefor, and with several external voltage sources of differentvalues, to produce a high velocity stream of electrons. Such operationis conventional, and need not be discussed in detail for anunderstanding of the invention.

In especial accordance with the invention, and with further reference toFIGS. 2 and 3, the cathode structure comprises a single cathode plate 21that supports the three operating cathode elements, there being one suchelement per gun. Support plate 21 includes three mounting spades 25,each embedded in a correspondingly positioned glass rod 14. The cathodestructure further includes three cathode sleeves 20, each disposed in aneyelet 22 mounted in an aperture 23 in plate 21. The sleeves 20conveniently are capped at their upper ends by an electron emissivematerial 28 of known type. The lower ends of sleeves 20 flare outwardlyinto supporting engagement with generally triangularly shaped lowerportions of eyelets 22, which arrangement is conventional.

Unlike conventional practice, fused glass frit 24 joins eyelet 22 tosupport plate 21, the frit also serving in an electrically insulativecapacity preventing electrical contact between adjacent operatingcathode elements. Advantageously, the plate 21 and its spades 25 arefabricated, using metal stamping techniques, as a single unit havingthree apertures 23 through which the eyelets 22 extend, and while it hasbeen shown as being substantially flat, plate 21 will be bent slightlyto position the cathodes at the gun convergence angle.

In assembly of the cathode structure, a bead of glass frit paste isapplied between flange 26 of the cathode eyelets 22 and plate 21, sothat the frit paste occupies the space between the eyelet flange 26 andconfronting adjacent portions of support plate 21 as the eyelets areurged into position. The elements thus subassembled are then fired tofuse, or mature, the glass frit paste. The cathode plate and sleeveassembly is then available for assembly into the gun structure, and forinsertion of the cathode sleeve 20 and associated heater 27 into theeyelets 22, in accordance with conventional practice.

It will be appreciated that the gun assembly, and the required alignmentprocedures, are greatly simplified by this invention, since it is nolonger necessary to maintain three separate cathode assemblies inprecise relative alignment with beading the same in the glass rods.

With reference to FIGS. 4 and 5, another embodiment of the invention isshown, which is especially adapted for disposition in single gunstructure provided with three cathodes for emitting a like number ofbeams, i.e. Trinitron type construction. Again, a cathode support plate30 is provided with three 'integrally formed spades 31 that are embeddedin corresponding ones of a like number of insulative support rods 32.Plate 30 comprises three apertures 33 in an in-line array, that isaligned diametrically across the plate. Cathode eyelets 34 are mountedwithin apertures 33 by the annular bodies of glass frit 35 disposedbetween eyelet flanges 36 and confronting surfaces of the plate 30. Theeyelets 34 receive and support the cathodes 37 with their emissiveregions 38 disposed in axial alignment with apertures 39 in the controlgrid 40, as shown.

It will be understood that, for either embodiment of the invention, thethermal expansion characteristics of the cathode support plate, thecathode eyelets, and the glass frit will be selected so as to be closelymatched. For example, the metal elements may comprise an alloy ofnickel, such as stainless steel, and the'glass frit may comprise a glassof the kind available under the trademark Corning 7575.

I claim:

1. In cathode ray tube electron gun structure of the type including aplurality of electrically insulative rods supporting a plurality ofassociated electrode elements including apertured control grid means,improved shielded cathode structure comprising: a unitary metalliccathode mounting plate supported on said rods and having three aperturesaligned with corresponding apertures of said control grid means; ametallic cathode eyelet mounted in each of said apertures in said plate,each said eyelethaving a peripheral, transversely extending mountingflange overlying planar surface portions of said plate on the sideremote from said grid means, said portions immediately surrounding theapertures therein; and an annular body of fused glass frit interposedbetween each said eyelet and said plate and between each said mountingflange and the confronting overlain surface portions of said plate, andproviding insulative mounting of each said eyelet in said plate, eachsaid eyelet supporting a cathode sleeve having an open end portion andan opposite, walled end portion provided with electron emissive materialconfronting a corresponding one of said apertures of said control gridmeans said cathode mounting plate including support spades formedintegrally therewith and having portions embedded in said insulativerods.

1. In cathode ray tube electron gun structure of the type including aplurality of electrically insulative rods supporting a plurality ofassociated electrode elements including apertured control grid means,improved shielded cathode structure comprising: a unitary metalliccathode mounting plate supported on said rods and having three aperturesaligned with corresponding apertures of said control grid means; ametallic cathode eyelet mounted in each of said apertures in said plate,each said eyelet having a peripheral, transversely extending mountingflange overlying planar surface portions of said plate on the sideremote from said grid means, said portions immediately surrounding theapertures therein; and an annular body of fused glass frit interposedbetween each said eyelet and said plate and between each said mountingflange and the confronting overlain surface portions of said plate, andproviding insulative mounting of each said eyelet in said plate, eachsaid eyelet supporting a cathode sleeve having an open end portion andan opposite, walled end portion provided with electron emissive materialconfronting a corresponding one of said apertures of said control gridmeans said cathode mounting plate including support spades formedintegrally therewith and having portions embedded in said insulativerods.